The Research Of EPDM Nonlinear Composites And Their Application In The DC Cable Termination

HVDC cable lines have the advantages of low loss, high transmission capacity,high operation stability, unlimited transmission distance and connected asynchronouspower grids, so the application is attracting increasing attention. High voltage DCpower cable accessories is an important part of DC cable lines, but also the weakestpart of the line. Since there are many factors that can influence the distribution ofelectric field in the DC cable accessories, and the manufacture of high-voltage DCcable accessories is rather difficult, it is still not possible to produce such products ofstable performance in domestic, which to a certain extent, limits the construction anddevelopment of XLPE high voltage DC cable line in our country. One of the methodsto solve the problem is to enhance the insulation material development andapplication of high performance.In this paper, the nano-composite materials are prepared by melt blendingEPDM rubber and inorganic fillers of nano silica (SiO2), nano silicon carbide (SiC),nano carbon black, nano graphite and so on. We study on the effect of adding amountof nano inorganic filler, compound on the mechanical properties of the composite,DC breakdown characteristics, characteristics of electrical conductivity and spacecharge distribution etc. We use COMSOL Multiphysics simulation software tocalculate the electric field distribution in HVDC cable accessories with EPDMmatrix composites as reinforced insulation. The results show that adding rightamount of nano SiO2can improve the mechanical properties of EPDM composites.When adding20phr nano SiO2, best mechanical properties can be obtained. With thecontent of nano SiC increasing, the conductivity of EPDM composites decreases andthen increases. When the content of nano SiC are50phr and60phr, the conductivityincreases rapidly nonlinearly under high electric field. Adding the right amount ofnano SiC, nano carbon black, nano graphite can effectively restrain the space chargeinside the EPDM composite material accumulation.